package com.bo.day20231215;

import java.util.Arrays;

/**
 * 统计排序：非比较排序,基于桶思想排序,只能用于0-200排序,如果大于就会需要更大的空间和时间
 * 例如：
 * arr={11,5,3,9,1,0,0,1}
 * bucket={2,2,0,1,0,1,0,0,0,1,0,1}
 * bucket={0,1,2,3,4,5,6,7,8,9,10,11}
 * bucket的长度为arr中的最大数
 * 在把bucket中的数拿出来排序接口
 *
 * @Author: gpb
 * @Date: 2023/12/18 15:08
 * @Description:
 */
public class CountSort {

    // for test
    public static void main (String[] args) {
        System.out.println(23/10);
        int testTime = 500000;
        int maxSize = 100;
        int maxValue = 150;
        boolean succeed = true;
        for (int i = 0; i < testTime; i++) {
            int[] arr1 = generateRandomArray(maxSize, maxValue);
            int[] arr2 = copyArray(arr1);
            countSort(arr1);
            comparator(arr2);
            if (!isEqual(arr1, arr2)) {
                succeed = false;
                printArray(arr1);
                printArray(arr2);
                break;
            }
        }
        System.out.println(succeed ? "Nice!" : "Fucking fucked!");

        int[] arr = generateRandomArray(maxSize, maxValue);
        printArray(arr);
        countSort(arr);
        printArray(arr);

    }

    public static void countSort (int[] arr) {
        if (arr == null || arr.length == 0) {
            return;
        }
        int max = Integer.MIN_VALUE;
        for (int i : arr) {
            max = Math.max(max, i);
        }
        int[] bucket = new int[max + 1];
        // 统计每个数出现的次数
        for (int i : arr) {
            bucket[i]++;
        }
        int index = 0;
        for (int i = 0; i < bucket.length; i++) {
            while (bucket[i]-- > 0) {
                arr[index++] = i;
            }
        }
    }

    // for test
    public static void comparator (int[] arr) {
        Arrays.sort(arr);
    }

    // for test
    public static int[] generateRandomArray (int maxSize, int maxValue) {
        int[] arr = new int[(int) ((maxSize + 1) * Math.random())];
        for (int i = 0; i < arr.length; i++) {
            arr[i] = (int) ((maxValue + 1) * Math.random());
        }
        return arr;
    }

    // for test
    public static int[] copyArray (int[] arr) {
        if (arr == null) {
            return null;
        }
        int[] res = new int[arr.length];
        for (int i = 0; i < arr.length; i++) {
            res[i] = arr[i];
        }
        return res;
    }

    // for test
    public static boolean isEqual (int[] arr1, int[] arr2) {
        if ((arr1 == null && arr2 != null) || (arr1 != null && arr2 == null)) {
            return false;
        }
        if (arr1 == null && arr2 == null) {
            return true;
        }
        if (arr1.length != arr2.length) {
            return false;
        }
        for (int i = 0; i < arr1.length; i++) {
            if (arr1[i] != arr2[i]) {
                return false;
            }
        }
        return true;
    }

    // for test
    public static void printArray (int[] arr) {
        if (arr == null) {
            return;
        }
        for (int i = 0; i < arr.length; i++) {
            System.out.print(arr[i] + " ");
        }
        System.out.println();
    }
}
